The Chicago WIHS Consortium (CWC) is comprised of Cook County Hospital's Women and children with HIV Program (CCHWCHP), University of Illinois (UIC), Rush Presbyterian St. Luke's Hospital (Rush), and Northwestern Memorial Hospital (NMH). Dr. Mardge Cohen (CCHWCHP) is the Principal Investigator and the Co-Principal Investigators are Drs. Catherine Deamant (CCHWCHP), Ronald Hershow (UIC), Constance Benson (Rush), and Patricia Garcia (NMH). CWC will enroll 250 HIV-infected women and 50 HIV negative at-risk women for at least three years to determine the natural history of HIV infection in women, to determine the incidence and co-factors of HIV infection in HIV-women, and evaluate vaccine feasibility. The CWC investigators have expertise in the design and conduct of collaborative HIV epidemiologic studies and clinical trials, particularly in women, people of color, and drug users which will enhance the Executive Committee and the Working Groups ability to establish scientific priorities, final data set and modules, and overall study direction.